Vehicle

ABSTRACT

The present invention discloses a vehicle ( 1 ) capable of being converted between a flying condition and an automotive riding condition. The vehicle has a telescopically extendable tail ( 10 ) comprising a first tubular tail segment ( 11 ) and a second tail segment ( 12 ) disposed axially slideable within the first tubular tail segment. The tail is provided with at least two form-closing coupling members ( 21, 35; 31, 36 ) located at an axial distance (LI) from each other for providing a force-transferring coupling between the second tail segment ( 12 ) and the first tubular tail segment ( 11 ) in the extended state of the second tail segment ( 12 ), each of said form-closing coupling members ( 21, 35; 31, 36 ) capable of transferring torque and transverse forces, and each of said form-closing coupling members ( 21, 35; 31, 36 ) coming into engagement by axial displacement of the second tail segment ( 12 ) in the outward direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a US National Stage of International Application No.PCT/NL2012/000070, filed 9 Nov. 2012, which claims the benefit of NLApplication 1039163, filed 11 Nov. 2011, both herein fully incorporatedby reference.

FIELD OF THE INVENTION

The present invention relates in general to a vehicle capable of flyingin air. Typically, it is customary for airplanes and helicopters to beeither flying or standing on the ground, in a parking condition.Nevertheless, it is customary for airplanes and helicopters to havewheels, so that they can be displaced over ground, for instance towardsand from a parking location. Airplanes and helicopters may even rideover land, for instance during take-off or landing or during taxiing:except during landing when they already have airspeed, they use theirair-propulsion for creating forward groundspeed. However, such groundtravel is typically over a relatively short distance at a relatively lowspeed (except for take-off or landing), and such air-vehicles are notsuitable for participating in road traffic.

On the other hand, for road traffic, cars have been developed, and theymust meet requirements regarding size, manoeuvrability, safety, etc.These requirements are not met by flying vehicles, and airplanes andhelicopters are not certified for use in traffic on public roads.

While flying machines are not equipped for road traffic, cars are notequipped for flying. Nevertheless, it is desirable to have a vehiclethat can be converted from a flying condition to an automotive ridingcondition, and vice versa.

Specifically, the present invention relates in general to a combinedland and air vehicle, i.e. a vehicle that can operate in a flying modein which it is capable of flying in air and in an automotive riding modein which it can drive on a road, much like a car. The requirements tothe configurations in both operating modes are quite different, and itis a challenge to make the vehicle in such a manner that allrequirements will be met and that changing the configuration from onemode to the other or vice versa can be done in an easy, safe andreliable manner.

One aspect of the present invention relates to the tail. In the flyingmode, the vehicle has a relatively long tail for stability. In theriding mode, such long tail is not needed, can be considered ahindrance, and it may even be that the overall length is too long withrespect to traffic regulations. Therefore, it is desirable that the tailis extendable for a transition from the riding mode to the flying modeand retractable for a transition from the flying mode to the ridingmode. It is noted that a retractable tail is also useful for flyingmachines which do not have such riding mode, to allow the flying machineto be parked or transported while requiring less space.

In the extended flying mode, the tail is subjected to several forces,which must be transferred reliably to the main body of the vehicle.Therefore, the extended tail must be fixed reliably. When the user makesa mistake in extending the tail, the consequences can be dramatical ifthe tail is not fixed correctly. The present invention aims to providean extendable tail design that can easily and almost error-free behandled by user.

The tail is provided with movable parts such as rudders and/or ailerons,which are controlled by cables. These cables have a length adapted tothe tail in its extended state. When the tail is retracted, these cablesare too long, and if the cables are not in a tightened state they sagand may become stuck in the mechanism. One obvious solution might be touse an automatic roller for winding the excess length of cable, but thismay lead to higher steering forces being needed and/or an increased riskof a cable getting stuck. The present invention aims to overcome thisproblem without the need of any user action.

For propulsion in the flying mode, the vehicle may comprise a propellermounted at the rear of the vehicle. The span of the propeller defines aforbidden area for the tail. The present invention aims to provide adesign for an extendable tail that can be combined with a propeller.

For providing lift in the flying mode, the vehicle requires a rotorhaving rotor blades of considerable length. In the riding mode, thoseblades are too long, so it is required to reduce the length of the rotorblades. While this requirement is known per se (see for instanceWO-2006/041287), it is difficult to provide a reliable solution thatcombines sufficient strength with good aerodynamic behaviour andacceptable manufacturing costs. The present invention aims to providesuch design.

It is to be noted that many of the features of the present invention arealso advantageous for a vehicle that is intended for flight only buthaving a retractable tail and foldable rotor blades for reducing thespace requirements during transport and/or storage.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further explained by the followingdescription of one or more preferred embodiments with reference to thedrawings, in which same reference numerals indicate same or similarparts, and in which:

FIG. 1 is a schematic side view of a vehicle according to the presentinvention;

FIGS. 2A-2C are a schematic longitudinal cross sections of a portion ofa telescopically extendable tail beam;

FIG. 3 illustrates details of a toothed coupling;

FIGS. 4A-4D are schematic side views of a ride/fly vehicle, showing thetransition from road riding condition to flying condition;

FIG. 5 is a schematic top view of a ride/fly vehicle;

FIG. 6A is a schematic perspective view of a longitudinal sectionedcable coupling arrangement;

FIGS. 6B and 6C are schematic longitudinal sections of this arrangementat a larger scale;

FIG. 7 is a schematic cross section of a rotor blade;

FIG. 8A is a schematic top view of the rotor blade;

FIG. 8B is a schematic side view of a portion of the rotor blade at alarger scale;

FIGS. 9A to 9C are views illustrating the joint between rotor bladesections according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 schematically shows a vehicle 1 according to the presentinvention, comprising a main body or cabin 2 with wheels 3 and anextendable tail 10 mounted at the rear of the cabin 2. Propulsion meanssuch as a propeller are not shown for sake of simplicity, and the sameapplies to lifting means such as a rotor. The vehicle 1 may have anautomotive riding condition, in which it can drive on a road, in whichcase it comprises a motor 4 for driving at least one of the wheels 3.

The extendable tail 10 comprises at least one extendable tail beam 13and a tail plane 14 mounted at the rear end of the tail beam 13. Thetail beam 13 is extendable telescopically, and comprises a first tubulartail section 11 attached to the cabin 2 and a second tubular tailsection 12 telescopically coupled to the first tail section 11. It isnoted that the first tail section may be fixed with respect to the cabin2 or may alternatively be extendable with respect to the cabin. It isfurther noted that the first tail section may be mounted at the rear ofthe cabin 2, as shown, but alternatively it is possible that the firsttail section 11 is mounted at least partly above or below the cabin 2,or even within the cabin 2. It is further noted that the extendable tailbeam 13 may include more than two sections telescopically coupled toeach other. It is further noted that the tail sections 11, 12 are shownas straight tubes, but in practice such tubes may have some curvature.It is further noted that the second tail section 12 may be solid if itis not necessary that control cables run internally in the second tailsection, but even then a hollow tube is preferred to save weight. It isfurther noted that the outer tube may be the rear tube while the innertube is attached to the cabin. In case there are two or more tail beams,the above description applies to each tail beam.

The extendable tail 10 comprises a blocking mechanism that is not shownin FIG. 1. This blocking mechanism assures that the extended conditionof the tail 10 is maintained during flight.

At its free end, the second tail section 12 carries the tail plane 14.Due to aerodynamic phenomena and inertia, the tail plane 14 exertsseveral forces on the second tail section, notably lateral forces Fx,transverse force Fy, vertical force Fz, and torque T. Further, thetransverse and vertical forces cause a bending momentum in the tail. Inthe extended condition, the connection between the first and second tailsections 11, 12, hereinafter also indicated as tubes, needs to be suchthat said forces are securely transferred onto the first tube 11 andfinally onto the cabin 2. The connection needs to be without play, sinceplay leads to wear and tear of the connecting parts. On the other hand,after flight it should be relatively easy to disengage the connectionand to retract the tail without the need of special equipment andwithout the need to exert large forces: the pilot should be able to doit manually himself. Conversely, before flight, the pilot should be ableto manually extend the tail and to manually activate the blockingmechanism, in an easy manner with simple actions, and the design shouldbe such that the chances on errors, which would cause the blockingmechanism to be fastened inadequately so that it may come loose duringflight, are minimal.

FIG. 2A is a schematic longitudinal cross section of a portion of thetail beam 13, illustrating the design proposed by the present invention.In the orientation of the drawing, the front ends of the tubes aredirected to the right and the rear ends of the tubes are directed to theleft, as in FIG. 1. The direction to the right corresponds to thedirection in which the second tube 12 is slid into the first tube 11,hence this direction will also be indicated as “inward direction”, whilethe opposite direction will also be indicated as “outward direction”.

At its rear end, the first tube 11 has a first toothed ring 21 attachedto its inner surface, with teeth 22 directed to the front end of thisfirst tube. In the following, this will be denoted as the first ring 21having teeth 22 at its front face. The inner diameter of the first ring21 is substantially equal to, preferably slightly larger than, the outerdiameter of the second tube 12. The inner surface of the first ring 21functions as bearing for slidably supporting and centering the secondtube 12 within the first tube 11. In order to minimize friction, theinner surface of the first ring 21 may be provided of a low-frictioncoating or shell 23.

At its front end, the second tube 12 has a second toothed ring 31attached to its outer surface, with teeth 32 at its rear face. The outerdiameter of the second ring 31 is substantially equal to, preferablyslightly smaller than, the inner diameter of the first tube 11. Theouter surface of the second ring 31 functions as bearing for slidablysupporting and centering the first tube 11 around the second tube 12. Inorder to minimize friction, the outer surface of the second ring 31 maybe provided of a low-friction coating or shell 33.

At a first distance L1 directed towards the front with respect to thefirst ring 21, the first tube 11 has a third toothed ring 26 attached toits inner surface, with teeth 27 at its front face. At a second distanceL2 directed towards the rear with respect to the second ring 31, thesecond tube 12 has a fourth toothed ring 36 attached to its outersurface, with teeth 37 at its rear face. The second distance L2 issubstantially equal to the first distance L1. The inner diameter of thethird ring 26 is larger than the outer diameter of the fourth ring 36.

The size of the distances L1 and L2 is not critical. However, since thecoupling should be capable of transferring bending moments, L1 and L2should not be too small. On the other hand, large values of L1 and L2are impractical. Taking the outer diameter of the second tail section 12as reference, L1 and L2 are preferably 1 to 10 times said diameter, morepreferably 3 to 6 times said diameter, while a practically proven valueis 4 times said diameter.

With the arrangement as described, the second tube 12 can telescopicallyslide towards the front, into the first tube 11. The first and secondrings 21 and 31 will keep the tubes 11, 12 centered with respect to eachother, and the third and fourth rings 26 and 36 will pass each otherwithout touching each other. Alternatively, the first and second rings21 and 31 are free from the opposing tubes, and each tube is providedwith separate centring means. Such centring means may be provided asseparate rings, or as blocks attached to the first and second rings 21and 31. Further, instead of sliding blocks, the guiding facility may beprovided by rotating balls.

The second tube 12 can travel into the first tube 11 until meeting astop (not shown for sake of simplicity) defining the extreme retractedposition of the second tube 12. FIG. 2B is a view comparable to FIG. 2A,showing the second tube 12 in a more retracted state.

To extend the tail 10, the second tail section 12 is telescopically slidtowards the rear, out of the first tail section 11. The first and secondrings 21 and 31 will keep the tail sections 11, 12 centered with respectto each other, and the third and fourth rings 26 and 36 will pass eachother without touching each other. The second tube 12 is slid out of thefirst tube 11 until the first toothed ring 21 of the outer tube 11engages the fourth toothed ring 36 of the inner tube 12 while at thesame time the third toothed ring 26 of the outer tube 11 engages thesecond toothed ring 31 of the inner tube 12.

FIG. 2C is a view comparable to FIG. 2A, showing the second tail section12 in its extreme extended position. It is noted that, during flight,aerodynamic drag tends to keep the second tail section 12 extended.Nevertheless, it may be desirable to have blocking means for positivelypreventing the second tail section 12 from sliding back into the firsttail section 11. Such blocking means will normally not need to withstandlarge forces. In the embodiment shown, the blocking means areimplemented as a transverse blocking pen 40, to be received in atransverse hole 41 of the first tail section 11. This blocking pen 40may be threaded and/or tapered. It is noted that the blocking pen isshown exaggeratedly large in the figure.

In this extended state, the inner tube 12 is force-coupled to the outertube 11 at two axially separated locations, i.e. a first coupling isconstituted by the engaging first and fourth rings 21, 36 and a secondcoupling is constituted by the engaging second and third rings 31, 26.This allows for a good transfer of transversal forces, bending momentsand torque. Lateral forces trying to draw the second tube 12 to the rearwill be accommodated by said rings, acting as axial stops. Lateralforces trying to push the second tube 12 to the front, back into theouter tube 11, will be non-existing or only very small and can easily becounteracted by the blocking pen 40, which therefore does not need to beexcessively large.

It should be clear that the required actions for converting the tailfrom its riding condition to its flying condition or vice versa arerelatively simple. After flight, the pilot simply removes the pen 40 andpushes second tail segment 12 into the first tail segment 11.Conversely, before flight, the pilot simply pulls out the second tailsegment 12 and inserts the blocking pen 40. If the second tail segment12 is not in the correct position, it will be impossible to insert theblocking pen 40. On the other hand, if the blocking pen is inserted,this is visual proof that the second tail segment 12 is in the correctposition.

FIG. 3 is a schematic side view of a part of the toothed rings 21, 36 toshow a possible embodiment of the shape of the teeth 22, 37. The samewill apply for the rings 31, 26. While several variations will bepossible, the teeth 22, 37 should have side faces 24, 38 making a slightangle φ with the axial direction. This angle φ should be larger thanzero to make the teeth self-centering and to assure that the teethengage and disengage easily. However, this angle φ should not be toolarge because then torque would lead to larger axial forces tending todisengage the teeth during flight. While a skilled person can easilyfind a value for said angle φ suitable in his particular design,depending on friction coefficient and manufacturing tolerances, ingeneral an angle of about 6 degrees will be adequate.

It is noted that the cross-sectional contour of the tubes 11, 12 may becircular, but although that may be most conveniently to implement it isnot essential. The present invention can also be implemented with tubeshaving for instance a rectangular or elliptical or oval cross-sectionalcontour.

It is further noted that a tail may comprise two or more telescopic tailbeams mounted in parallel to achieve better stiffness and/or to be ableto use tubes with smaller diameters.

In FIG. 1, the tail 10 is depicted as being mounted directly to thecabin 2. While there may indeed be situations where such design issatisfying, it does not lead to an optimal solution of the problems indesigning a vehicle that should be able to be converted from a roadriding configuration to an air flying configuration and back. In theflying configuration, the vehicle will have a propulsion propeller atthe back, a lifting rotor on top, and a tail plane with ailerons held atsome distance to the rear of the cabin. In the road ridingconfiguration, the overall vehicle should be as compact as possible andit should have a center of gravity as low as possible. In the flyingconfiguration, the rotation axis of the propeller should ideallyintersect the center of gravity, and although some tolerance isacceptable, a low center of gravity means that the propeller must bemounted low so that the radial length of its propeller blades is limitedsince these blades must remain free from the ground. On the other hand,with a view to efficiency, it is desirable to have large radial lengthof the propeller blades.

The present invention proposes a solution for these design problems. Atits upper side, the vehicle is provided with a collapsible mast carryingboth the rotor and the tail. In the flying condition, the mast is in anupright condition, so the tail is raised and extends over the propellerblades. In the road riding condition, the mast is folded forwards to ahorizontal condition, so that the tail lies close to the cabin roof andthe overall vehicle is quite compact. This will be explained in moredetail with reference to FIGS. 4A-4D, which are side views schematicallyshowing the transition from road riding condition to flying condition.

FIG. 4A illustrates the road riding condition of the vehicle 1. It willbe seen that the tail 10 lies close to the roof of the cabin 2, and thatthe tail plane 14 is close to the cabin, so that the vehicle 1 is verycompact.

FIG. 4B illustrates that, as a first step in the conversion processtowards the flying condition, the tail 10 is extended. It can berecognized in this figure that the tail 10 comprises the extendable tailbeam with telescopic tail segments 11 and 12 as described earlier, andthat these segments are slightly curved in order to have the tail beamconform to the curved aerodynamic shape of the cabin 2.

FIG. 4C illustrates that the vehicle 1 comprises a main mast 50 that ishinged to the roof of the cabin 2.

At its upper end, the mast 50 carries the rotor (see FIG. 4D). At itslower end, the mast 50 is hinged to the roof of the cabin 2, with ahorizontal hinge axis 52 transverse to the longitudinal direction of thevehicle 1. At a position lower than the upper end of the mast 50, thetail 10 is hinged to the mast 50, with a horizontal hinge axis 51parallel to the lower hinge axis 52. At some distance rearward of themast 50, the vehicle 1 has a support structure 60 parallel to the mainmast 50, also hinged to the roof of the cabin 2 with a hinge axis 62,and also hingedly supporting the tail 10 with a hinge axis 61. Inprojection onto a virtual midplane, these four hinges define aquadrangle that approximates a parallelogram. The mutual distancebetween the hinges on the main mast 50 may differ from the mutualdistance between the hinges on the support structure 60, and/or themutual distance between the hinges on the cabin roof may differ from themutual distance between the hinges on the tail, to define a correctpositioning of the tail with respect to the cabin in the road ridingcondition and to define a correct tail positioning in the flyingcondition.

In the FIGS. 4A and 4B, the mast 50 and support structure 60 lie loweredto the cabin roof so that they are not clearly visible. In FIG. 4C, themast 50 and support structure 60 are being hinged to their uprightcondition, while in FIG. 4D this movement has been completed and themast 50 and support structure 60 stand fully upright. Reference numeral53 indicates a lock for locking the main mast 50 in its uprightcondition. A mechanism for erecting or lowering the mast 50 and supportstructure 60 may for instance comprise a hydraulic cylinder, mounted inthe mast 50, but this is not shown for sake of simplicity.

In FIG. 4D, also the propeller 80 and the rotor 90 are shown. It will beseen that, at least in this flying condition, the blades of thepropeller 80 can be relatively long, extending to above the cabin roof,while the tail 10 clearly extends over the propeller. It is further tobe noted that with the raising of the mast 50 its upper end has beendisplaced to the rear of the vehicle, bringing the tail plane 14 furtherrearwards.

In a preferred embodiment, the tail 10 comprises two mutually paralleltail beams 13A and 13B arranged next to each other. This is not visiblein the side views of FIGS. 4A-4D, but is schematically illustrated inthe schematic top view of FIG. 5. The two tail beams 13A and 13B aremounted on opposite sides of the mast 50 and support structure 60. Attheir rear ends, the tail beams 13A and 13B are connected by ahorizontal beam 15, which may be integrated with or implemented as tailfoil. The tail 10 may comprise a single vertical tail plane or foil 14mounted in the center of the horizontal foil 15, but it is preferredthat the tail 14 comprises two vertical tail planes 14A and 14B at amutual horizontal distance. It is noted that this is also possible inthe case of a tail with a single tail beam. In the retracted conditionof FIG. 4A, the two tail planes can be located on opposite sides of therear portion of the cabin, as shown, for which purpose the cabin mayhave a slender rear portion giving the entire cabin a drop-shape.

In the figures, no constructive details are given of the supportstructure 60. In FIG. 5, the support structure 60 is shown as a singlemast or pilar, which is a possible embodiment, indeed. Preferably,however, the support structure 60 is designed to increase transversestability and torsion stability while adding as little weight aspossible. To this end, the support structure 60 may comprise two (ormore) mutually parallel masts mutually interconnected by diagonal crossbeams.

As is illustrated in FIG. 4D, a tail plane 14 may comprise one or morerudders or ailerons 16. In such case, control cables for such aileron(shown at 70 within the cabin) are guided within the hollow tail beam13. The length of such control cable should be adapted to the length ofthe tail beam 13 in its extended state, which implies that such controlcable would be too long for the tail beam in its retracted state.Winding the excess length of cable on a roll involves introduction of awinding mechanism that may introduce the risk of getting stuck and/orleading to increased steering forces.

The present invention proposes a solution to these problems, whichinvolves implementing the cables in two parts that can shift axiallywith respect to each other. This solution will be explained withreference to FIGS. 6A and 6B, wherein FIG. 6A is a schematic perspectiveview of a longitudinal section while FIG. 6B is a schematic longitudinalsection on a larger scale. It is noted that the relative sizes of thedifferent components are not necessarily shown to scale.

Both figures show a portion of control cable assembly 100. This controlcable assembly 100 runs within an extendable tail beam as described inthe above, but for sake of simplicity such tail beam is not shown inFIGS. 6A and 6B. Normally, a cable runs as an integral whole from acontrol member (such as a pedal) to a controlled member (such as anaileron). According to a key aspect of the invention, the cable assembly100 comprises a first cable part 110 having a first end (not shown)attached to a control member in the cabin and having an opposite freeend 111, a second cable part 120 having a first end (not shown) attachedto a controlled member at the end of the tail and having an oppositefree end 121, and a coupling arrangement 130 coupling the free ends 111,121 of the two cable parts 110, 120. It is noted that the cable may bedivided in three or more cable parts, wherein always two subsequentcable parts are coupled by a respective coupling arrangement 130.

The first cable part 110 is accommodated, at least over a part of itslength, in a cable sheath 112 having an inner diameter only slightlylarger than the outer diameter of the first cable part 110 so that thefirst cable part 110 can slide freely in axial direction within thecable sheath 112. The cable sheath 112 is fixed to the end of the firsttail segment closest to the cabin 2, i.e. the outer tube 11 of FIGS. 1and 2A-2C. The cable sheath 112 should have sufficient stiffness, aswill become clear later, yet a certain level of flexibility ispreferred. A suitable material may be plastic.

The coupling arrangement 130 comprises a coupling tube 140 that is fixedwith respect to the second tail segment directed away from the cabin,i.e. the inner tube 12 of FIGS. 1 and 2A-2C. At a first end 141, thetube 140 receives the free end of the first cable part 110 and its cablesheath 112. At its first end 141, the tube 140 is closed by a first plug143 having an axial bore 144. This bore has a curved, trumpet-shapedentrance portion, narrowing towards the interior of the tube 140, toallow for mis-alignment between tube 140 and sheath 112. The oppositeend of said bore has a straight end portion, which is the narrowestlocation, where the inner diameter of the bore 144 is slightly largerthan the outer diameter of the cable sheath 112, so that the cablesheath 112 can slide freely through the bore 144.

At its opposite second end 142, the tube 140 receives the free end ofthe second cable part 120. Although not essential, it is preferred thatthe second cable part 120 is accommodated, at least over a part of itslength, within a guiding tube 122. At its second end 142, the tube 140is closed by a second plug 145 having an axial bore 146. Facingoutwards, the second plug 145 has a chamber 147 receiving the end ofguiding tube 122. Facing inwards, the bore 146 has a funnel-shapedcatch-in portion 148. Adjacent the axial bore 146, the second plug 145has a bore 149 for passing the second cable part 120.

Inside the coupling tube 140, a sliding coupling block 150 is arranged,having an outer diameter slightly smaller than the inner diameter of thecoupling tube 140, so that the coupling block 150 can slide freelywithin the coupling tube 140 but can not tilt. The coupling block 150has a first end 151 directed to the first end 141 of the tube 140 and asecond end 152 directed to the second end 142 of the tube 140. Thecoupling block 150 has an axial bore 153, which at the first block end151 may be tapered, as shown. The axial bore 153 has an inner diameterslightly larger than the outer diameter of the cable sheath 112, so thatthe cable sheath 112 can slide freely through the bore 153.

The first cable part 110 extends through the bore 153 of the couplingblock 150. A stop 113 is fixed to the end 111 of the first cable part110, this stop having a diameter larger than the diameter of the bore153.

The end 121 of the second cable part 120 is fixed to the coupling block150, at any suitable location on the block 150.

It may be that the control cable 100 is used to control two or moremembers. In such case, it is convenient to connect two or more secondcable parts 120 to the coupling block 150, each of such respectivesecond cable parts running to the respective controlled member. However,even if the control cable 100 is used to control only one member (forinstance: aileron), it is nevertheless preferred that the second cablepart 120 is implemented by two or more mutually parallel cables 120A,120B which are attached to the coupling block 150 on opposite sides ofthe central bore 153, in a symmetrical manner, as shown, in order toavoid the generation of tilting forces on the block 150, which wouldundesirably increase friction of the block 150 within the tube 140.

The operation is as follows. FIG. 6B illustrates the situation when thetail 10 is in its extended state. It can be seen that the stop 113 ofthe first cable part 110 bears against the coupling block 150. The stop113 may be accommodated partly or wholly within the coupling block 150.When the pilot actuates the control cable 100, a pulling force (directedto the right in FIG. 6B) is exerted on the first cable part 110, causingthe coupling block 150 to be displaced within the coupling tube 140(towards the right in FIG. 6B) which in turn causes the second cablepart 120 to be pulled. In other words, the coupling block 150 hascoupled the two cable parts 110 and 120 firmly together for securelytransferring pulling forces. The inner length of the coupling tube 140,i.e. the distance between first plug 143 and second plug 145, definesthe free stroke of the coupling block 150 and hence the free stroke ofthe control pedals. In a suitable embodiment, this stroke may be in therange of for instance 10-25 cm.

In turn, the second cable part 120 pulls the member to be controlled inone direction. For pulling this member in the opposite direction, asecond cable assembly is present, identical to the cable assemblydescribed above, but this second cable assembly is not shown for sake ofsimplicity. Each cable assembly only transfers pulling forces. When thepilot pulls the first cable part 110 of said assembly 100, thecontrolled member pulls the second cable assembly, as should be clear toa person skilled in the art.

When the tail 10 is retracted, the tube 140 with the second cable part120 and the coupling block 150 is shifted towards the first cable part110 and its cable sheath 112. After all, the tube 140 with the secondcable part 120 and the coupling block 150 are fixed with respect to theinner tube 12 that is shifted to the right (in the figure) with respectto the outer tube 11, to which cable sheath 112 is fixed. Within thecabin 2, the control member to which the first cable part 110 isconnected is coupled to the cabin chassis under spring-bias, so thatthis control member is displaced in the cabin to keep the first cablepart 110 tight. With respect to the tube 140, the second cable part 120and the coupling block 150 and the first cable part 110 remainstationary while the cable sheath 112 is displaced towards the left. Thetail 10 can be retracted over a distance larger than the above-mentionedstroke; said distance may for instance be in the range of about 2 m.Thus, the free end of the cable sheath 112 will meet the block 150 andwill enter the central bore 153 thereof. Finally, the free end of thecable sheath 112 will abut the stop 113 at the free end 111 of the firstcable part 110.

At its narrowest location, the inner diameter of the bore 146 is largerthan the outer diameter of stop 113. With further retraction of thetail, the free end of the cable sheath 112 will take along the free end111 of the first cable part 110, and together they will move to theleft, depart from the block 150 and exit the coupling tube 140 throughthe bore 146 of the second plug 145, into the preferred guiding tube122. This situation is illustrated in FIG. 6C.

Thus, the first cable part 110 is maintained in a tensioned state at alltimes, avoiding the risk of a loose-hanging cable getting stuck.

When the tail is extended again, the above displacements take place inthe reverse direction. It is noted that the stop 113, at its sidedirected to the first cable part 110, may be tapered to facilitatecentering of the stop 113 with respect to the bore 153 in block 150 whenthe tail is extended.

FIG. 4D illustrates that the blades of the rotor 90 have a relativelylarge length. In the riding condition, such rotor 90 would be too largefor the vehicle. In order to keep the rotor blades within the desiredwidth profile of the vehicle in the riding condition, the rotor bladesare hingeable with respect to the mast 60, so that, in the ridingcondition, the rotor blades are directed substantially parallel to thetail 10. Nevertheless, the rotor blades will still be too long in thesense that they project beyond the rear end of the vehicle. In order toovercome this problem, the rotor blades may be foldable such as toreduce the blade length. This means that a rotor blade would consist oftwo (or more) blade sections that are hingedly connected to each other.

Foldable rotor blades have already been proposed before: reference ismade for instance to U.S. Pat. No. 7,857,590 and WO-2006/041287.However, implementing a foldable rotor blade poses problems which theprior art has not yet solved in a satisfying manner.

A first problem is that, in the flying condition, the blade sectionsmust be fixed with respect to each other in the folded-out condition,and the fixing arrangement must be sufficiently strong to accommodatethe huge centrifugal forces, bending moments and torque occurring in theblade. Further, vibration of the blade parts should be prevented as muchas possible, because vibration is annoying to the pilot and may lead tofailure of components through fatigue.

A second problem relates to aerodynamics. The hinge design should besuch that it has acceptable aerodynamic properties, taking into accountthat the wind velocity at the mid section of a rotor blade (which isabout the location of the hinge members) may easily be 300 km/h. A badaerodynamic shape may lead to energy loss and/or vibrations.

A third problem relates to costs. The design should be such that it canbe manufactured at reasonable cost.

The present invention offers a solution to the above problems, whichwill be explained with reference to FIG. 7 and further.

FIG. 7 is a schematic cross section of a rotor blade or foil 200,generally explaining a blade design made from composite materials thathas proved itself in practice. The blade 200 comprises an upper spar 201and a lower spar 202 arranged above each other, which are constituted bymainly unidirectional fiber material with the fiber oriented in thelength-direction of the blade, i.e. perpendicular to the plane ofdrawing. This fiber material is capable of accommodating high lateraltension forces, such as caused by centrifugal forces. The space betweenthe two spars 201, 202 is filled with a low-weight material 203, forinstance a foam or a honeycomb structure. At the front side of the spars201, 202, the blade 200 comprises a substantially D-shaped member 204that serves to increase the weight at the front side of the blade, toimprove stability; this member 204 may for instance comprise lead. Atthe trailing side of the spars 201, 202, the blade 200 consists mainlyof low-weight filling material 205, like the material 203. The blade'souter surface is defined by a skin layer 206 around the above-mentionedcomponents.

FIG. 8A is a schematic top view of the blade 200, illustrating that theblade 200 consists of two blade sections 221 and 222. Blade section 221is attached to a rotor hub 210 and will be indicated as inner bladesection. Blade section 222, which will be indicated as outer bladesection, is attached to the extreme end of the inner blade section 221,aligned therewith, in such a manner that the outer blade section 222 canhinge upwards with respect to a horizontal transverse hinge axis 223 tobe folded over the inner blade section 221.

FIG. 8B is a schematic side view of a portion of the blade 200 at alarger scale, showing the outer end 224 of the inner blade section 221and the inner end 225 of the outer blade section 222 in taken-apartcondition for sake of clarity. The outer end 224 of the inner bladesection 221 has an increased height as compared to the remainder of theinner blade section 221, and comprises two transverse coupling holes 226and 227 arranged above each other. Likewise, the inner end 225 of theouter blade section 222 has an increased height as compared to theremainder of the outer blade section 222, and comprises two transversecoupling holes 228 and 229 arranged above each other. In the coupledcondition, the upper coupling holes 226, 228 will be aligned with eachother, with a coupling pin 231 extending through said holes. This pinalso functions as hinge pin: for converting the rotor blade 200 to theriding condition, the outer blade section 222 can be hinged upwards withrespect to this pin 231 to be laid on top of the inner blade section221. In the flying condition, the outer blade section 222 will be hingeddown to a position aligned with the inner blade section 221 where thelower coupling holes 227, 229 are aligned with each other. The blade 200is secured in this position by inserting a locking pin 232 through saidlower coupling holes 227, 229.

Alternatively, the upper pin may be locking pin while the lower pin maybe hinge pin.

In the flying condition, forces will be transferred via the coupling pin231 and the locking pin 232. From the above description of the bladedesign, it will be clear that the forces mainly occur in the spars 201,202; the other blade components transfer hardly or no force in theblade's longitudinal direction. From this perspective, the precisemanner in which the other blade components 203, 204, 205, 207 are shapedat the outer end 224 of the inner blade section 221 and the inner end225 of the outer blade section 222 is not critical and has noconsequence for the present invention; therefore, these components willbe ignored in the following.

In a normal, unsectioned blade, the fibers in each spar always run overthe entire length of the blade. According to the present invention, eachfiber is laid in a vertical loop around one of said coupling holes.

FIG. 9A is a top view of the joint between inner blade section 221 andouter blade section 222 showing this inventive feature in more detail,and FIG. 9B is a perspective view of this joint. In FIG. 9B, the upperspar and lower spar of the inner blade section 221 are indicated byreference numerals 201A and 202A, respectively, while the upper spar andlower spar of the outer blade section 222 are indicated by referencenumerals 201B and 202B, respectively.

In each spar, the fibers are subdivided in bundles or groups. Each fibergroup in a spar is looped around in a vertical plane over an angle of180° and laid back next to itself, to define a coupling eye. FIG. 9C isa schematic side view of such coupling eye 300, which comprises asupport ring 301 and a support wedge 302, which may be separate orformed as an integral whole. A fibre group 303 consists of threesections: a first spar section 304, a loop section 305 and a second sparsection 306. The loop section 305 is looped around the support ring 301and the support wedge 302, and the second spar section 306 is positionednext to the first spar section 304. This is repeated for multiple fibergroups, wherein always the spar sections of adjacent groups arepositioned close together whereas the respective coupling eyes will bearranged at a mutual distance. It should be clear that all spar sectionstogether define the spar of a blade section.

In manufacture, a mould will be used in which several support rings plusaccompanying support wedges are held in the correct position and mutualdistance, having their central holes ligned, and in which separationwalls will keep the fibre groups confined. The resulting intermediateproduct will be a spar of a blade section, with integral coupling eyes.In a subsequent assembly step, two of such intermediate spar productswill be arrange on top of each other to form a blade section.

In FIGS. 9A and 9B, the upper spar 201B of the outer blade section 222comprises four fibre groups 311, 312, 313, 314 which define fourcoupling eyes 321, 322, 323, 324. The same applies to the lower spar202B of the outer blade section 222.

The upper spar 201A of the inner blade section 221 likewise comprisesfour fibre groups 331, 332, 333, 334 which define four coupling eyes341, 342, 343, 344. The same applies to the lower spar 202A of the innerblade section 221.

It can be seen that in the assembled condition coupling eyes of theouter blade section 222 are aligned with and alternate with couplingeyes of the inner blade section 221. This applies to the upper spar201A, 201B and to the lower spar 202A, 202B. Therefore, the differencebetween the number of coupling eyes of the inner blade section 221 andthe number of coupling eyes of the outer blade section 222 will usuallybe equal to zero or one.

In the embodiment of FIGS. 9A and 9B, the second and third coupling eye342, 343 of the inner blade section 221 are not arranged at a distanceto accept a coupling eye of the outer blade section in between them, butare located next to each other, so that they can be considered as onesingle coupling eye. This is however not necessary.

Generally speaking, the number of fibers in the upper and lower sparsections of the inner blade will be mutually substantially equal, andthe same applies to the upper and lower spar sections of the outerblade. When comparing inner blade and outer blade, the number of fibersin the inner blade will typically be larger than the number of fibers inthe outer blade, to accommodate for the fact that the loads in the innerblade are higher than the loads in the outer blade. Within a spar, it ispossible that the number of fibers decreases with increasing distancefrom the rotor center. The thicknesses of the coupling eyes may differ.In the embodiment shown, the thickness of the central coupling eye 342,343 of the inner blade section 221 is larger than the thickness of theother coupling eyes 341, 344 of the inner blade section 221, which inturn have a thickness equal to the coupling eyes of the outer bladesection 222. However, it is also possible that the inner blade section221 has three coupling eyes of mutually the same thickness, larger thanthe thickness of the coupling eyes of the outer blade section 222.

It is noted that the number of coupling eyes of a spar is not critical;this number is at least equal to 2, preferably 3 or 4 or 5. In the caseof a spar having a width of 12 cm, the fiber groups may for instancehave a width of 15 mm.

It is further noted that, in the assembled condition, an aerodynamicallyshaped cap will be arranged around the joint.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, it should be clear to a personskilled in the art that such illustration and description are to beconsidered illustrative or exemplary and not restrictive. The inventionis not limited to the disclosed embodiments; rather, several variationsand modifications are possible within the protective scope of theinvention as defined in the appending claims.

For instance, for driving the propeller 80, a separate motor may beprovided. However, it is also possible that the motor 4 is common forthe wheels 3 and the propeller 80, with switching means for directingthe motor output either to the wheels 3 or to the propeller 80.

Further, while it is possible to use a separate tube 140 fixed withrespect to the inner tube 12, it is also possible that the inner tube 12itself fulfils the role of tube 140. In such case, plugs 143 and 145 aremounted within the tubular tail section 12, defining between themselvesa portion of tail section 12 acting as inner space of tube 140 in whichthe coupling block 150 is disposed.

Other variations to the disclosed embodiments can be understood andeffected by those skilled in the art in practicing the claimedinvention, from a study of the drawings, the disclosure, and theappended claims. Any reference signs in the claims should not beconstrued as limiting the scope.

The invention claimed is:
 1. Telescopically extendable tail for a flyingvehicle comprising: at least one tail beam comprising a first tubulartail segment; and a second tail segment disposed within the firsttubular tail segment and axially slideable in an inward direction and inan outward direction; the tail beam being provided with at least twoform-closing coupling members located at an axial distance from eachother for providing a force-transferring coupling between the secondtail segment and the first tubular tail segment in an extended state ofthe second tail segment; wherein each of the form-closing couplingmembers are capable of transferring torque and transverse forces;wherein each of the form-closing coupling members coming into engagementby axial displacement of the second tail segment in the outwarddirection; wherein one of the form-closing coupling members comprise twointernal toothed rings, and the other one of the form-closing couplingmembers comprise two external toothed rings; and wherein the most inwardone of the internal toothed rings has an inner diameter larger than anouter diameter of the most outward one of the external toothed rings. 2.Tail according to claim 1, wherein the first tubular tail segment isprovided with the two internal toothed rings located at a first mutualaxial distance; wherein the second tail segment is provided with the twoexternal toothed rings located at a second mutual axial distancesubstantially equal to the first mutual axial distance; wherein bothinternal toothed rings of the first tubular tail segment have teethdirected in the inward direction; and wherein both external toothedrings of the second tail segment have teeth directed in the outwarddirection.
 3. Tail according to claim 2, wherein the most outward one ofthe internal toothed rings of the first tubular tail segment has aninner diameter substantially equal to an outer diameter of the secondtail segment; and wherein the most inward one of the external toothedrings of the second tail segment has an outer diameter substantiallyequal to an inner diameter of the first tubular tail segment.
 4. Tailaccording to claim 1 further comprising a blocking means for blockingthe second tail segment in its extended state.
 5. Tail according toclaim 4, the blocking means comprising a transverse blocking pen to beinserted transversely into the first tubular tail segment.
 6. Flyingvehicle comprising a tail according to claim
 1. 7. Vehicle beingconvertible between a flying condition and an automotive ridingcondition, the vehicle comprising: a tail according to claim 1; whereinin the flying condition the tail is extended while in the automotiveriding condition the tail is retracted.
 8. Telescopically extendabletail for a flying vehicle comprising: at least one tail beam, the tailbeam comprising a first tubular tail segment and a second tail segmentdisposed within the first tubular tail segment and axially slideable inan inward direction and in an outward direction; the tail beam beingprovided with a first form-closing coupling member for providing aforce-transferring coupling between the second tail segment and thefirst tubular tail segment in an extended state of the second tailsegment; wherein the first form-closing coupling member is capable oftransferring torque and transverse forces; and wherein the firstform-closing coupling member comes into engagement by axial displacementof the second tail segment in the outward direction; the tail beam beingprovided with a second form-closing coupling member for providing aforce-transferring coupling between the second tail segment and thefirst tubular tail segment in an extended state of the second tailsegment; wherein the second form-closing coupling member is capable oftransferring torque and transverse forces; and wherein the secondform-closing coupling member comes into engagement by axial displacementof the second tail segment in the outward direction; wherein the twoform-closing coupling members are located at an axial distance from eachother; wherein the first form-closing coupling member comprises twointernal toothed rings, and the second form-closing coupling membercomprises two external toothed rings; and wherein the most inward one ofthe internal toothed rings has an inner diameter larger than an outerdiameter of the most outward one of the external toothed rings. 9.Vehicle being convertible between a flying condition and an automotiveriding condition, the vehicle comprising: a tail according to claim 8;wherein in the flying condition the tail is extended while in theautomotive riding condition the tail is retracted.
 10. Telescopicallyextendable tail according to claim 8, wherein the internal toothed ringshave teeth directed in the inward direction; and wherein the externaltoothed rings have teeth directed in the outward direction. 11.Telescopically extendable tail according to claim 8, wherein the mostoutward one of the internal toothed rings has an inner diametersubstantially equal to an outer diameter of the second tail segment; andwherein the most inward one of the external toothed rings has an outerdiameter substantially equal to an inner diameter of the first tubulartail segment.
 12. Telescopically extendable tail according to claim 8further comprising a blocking means for blocking the second tail segmentin its extended state.
 13. Telescopically extendable tail according toclaim 12, wherein the blocking means comprises a transverse blocking peninserted transversely into the first tubular tail segment. 14.Telescopically extendable tail for a flying vehicle comprising: at leastone tail beam, the tail beam comprising a first tubular tail segment anda second tail segment disposed within the first tubular tail segment andaxially slideable in an inward direction and in an outward direction;the tail beam being provided with a first form-closing coupling memberfor providing a force-transferring coupling between the second tailsegment and the first tubular tail segment in an extended state of thesecond tail segment; wherein the first form-closing coupling member iscapable of transferring torque and transverse forces; wherein the firstform-closing coupling member comprises a first coupling element attachedto the first tubular tail segment and a second coupling element attachedto the second tail segment; and wherein the first coupling element andthe second coupling element of the first form-closing coupling membercome into engagement with each other by axial displacement of the secondtail segment in the outward direction; the tail beam being provided witha second form-closing coupling member for providing a force-transferringcoupling between the second tail segment and the first tubular tailsegment in an extended state of the second tail segment; wherein thesecond form-closing coupling member is capable of transferring torqueand transverse forces; wherein the second form-closing coupling membercomprises a first coupling element attached to the first tubular tailsegment and a second coupling element attached to the second tailsegment; and wherein the first coupling element and the second couplingelement of the second form-closing coupling member come into engagementwith each other by axial displacement of the second tail segment in theoutward direction; wherein the two form-closing coupling members arelocated at an axial distance from each other; wherein each of the firstand second coupling elements of the first form-closing coupling membercomprise an internal toothed ring, and each of the first and secondcoupling elements of the second form-closing coupling member comprise anexternal toothed rings; and wherein the most inward one of the internaltoothed rings has an inner diameter larger than an outer diameter of themost outward one of the external toothed rings.
 15. Vehicle beingconvertible between a flying condition and an automotive ridingcondition, the vehicle comprising: a tail according to claim 14; whereinin the flying condition the tail is extended while in the automotiveriding condition the tail is retracted.
 16. Telescopically extendabletail according to claim 14, wherein the internal toothed rings haveteeth directed in the inward direction; and wherein the external toothedrings have teeth directed in the outward direction.
 17. Telescopicallyextendable tail according to claim 14, wherein the most outward one ofthe internal toothed rings has an inner diameter substantially equal toan outer diameter of the second tail segment; and wherein the mostinward one of the external toothed rings has an outer diametersubstantially equal to an inner diameter of the first tubular tailsegment.
 18. Telescopically extendable tail according to claim 14further comprising a blocking means for blocking the second tail segmentin its extended state.
 19. Telescopically extendable tail according toclaim 18, wherein the blocking means comprises a transverse blocking peninserted transversely into the first tubular tail segment.